Hi guys, I am hoping I can get some feelers for what i need to be looking for to diagnose my car.

I built a fully forged 383 at 9.5:1 compression. I'm running a D1SC twin intercooled with a 13lb pulley. I have 60lb injectors, dual 255lph pumps (7lb hobbs). Fuel lines, regulator and rails are all stock. The only thing upgraded with regard to fuel system is pumps and injectors. I have new NGK boost plugs (Moe B recommended part and gap, so I think that's good). Newer plug wires. MSD 6AL with harness to avoid splicing. MSD blaster coil. Moe Bailey has spec sheet and did the tune. Fired up on first try and idles well. Also revs well in neutral. All issues are under load. I will update build list in sig for more details.

The way I routed the vented PCV is as follows:
PCV to catch can inlet (3/8" hose).
Catch can outlet to Passenger valve cover (1/2" hose).

My Vacuum is a steady 11in hg.

Once cruising it's OK, but when I stop it wants to stall and to get the RPM back up, it starts to sputter until it gets moving. My AFR is about 15.5 and never really goes below 15, so I know I'm leaning out. The boost is not getting over 5 PSI and the gauge goes a little wonky with the hiccups it's having.

I also noticed yesterday that after the few miles ride, I have oil leaking from the back and front, so I'm thinking rear main/front main have been pushed. It's either that, or leaky rear intake and another seal on front of engine.

Any help would be much appreciated, but I am leaning toward PCV setup, but I'm hoping some experience guys have some stuff I can look at.

PCV valve is stock new.

Car build:
97, OBD1 computer tuned by Moe B. Forged 383, D1SC @ 13lb, twin intercooled, comp 1.6 RR, LS lifters, DSE long tubes, MSD 6AL, MSD coil, dual 255lph fuel pumps (7psi hobbs), 60LB injectors, 2 bar MAP, NGK BR7EF .025" gap, vented catch can

 

I am in no way a pro at this and this should be taken with many grain of salt:
AFR Is terrible -Ensure that you're getting correct readings (ARF gauge is installed correctly, no exhaust leaks, ect) If its at 15 while you are hitting 5psi, do not keep doing that. Keep that thing out of boost until the tune is sorted out.
PCV - I am not sure on this setup, if you get any blow-by you are going to be pushing pressure into that can. I am not super familiar with LT1 PCV setups but I think consulting mightymouse solutions instructions is a good plan here. Very likely you are pushing out the front/rear main seal because this setup is not ideal. From what I recall (at least how I have my LS setup)- The intake on the procharger (between filter and procharger) provides vacuum for the catch can which is connected to the valve cover. That way the Can is always under vacuum even when you're in boost
Stalling when letting off the throttle - Try and sort out the AFR issue first because being that lean could just be running the thing dry. Otherwise, Idle Air Control counts probably need to be adjusted in the tune - You are very much shooting yourself in the foot using a stock computer, if you can get a Holley or something else, Haltech, Bigstuff3, anything like that, youd be in much better shape when it comes to assessing problems.

 

On my car the with Vortech S trim, the passenger valve cover hose goes to a Bung between the inlet side of the supercharger and air filter.

The pcv valve goes to the port under the throttle body. I have had that 90 degree hose come off before and was limited to 2-3# of boost. It now has hose clamps on it and won't come off.

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I ended up routing the driver valve cover to thr catch can using this 90 degree port for a jeep that had a .93" that fit the proform 1" grommet a little tight, but it works. I capped off the PCV valve. There is no longer oil leaking so my guess is that the way to route a catch can on a boosted LT1 is to run both valve covers to the catch and cap off all PCV ports on intake.

However, my drive problem remains, despite my AFR being right around 11.5-12, which is about what Moe said it should be (.8 lambda). I'm only getting 5 psi and it is choppy and then stumbles after i stop and go to accelerate again.

I've never been one to blame the opti. Ive done my fair share of troubleshooting and have ever only replaced the opti on this car once in 2006 when the factory unit failed. I'm running that same one today and I'm wondering if it could be a part of my problem.

Car also smells rich.

Just wanted to update this thread in case it ever helps a fellow LT1 guy in future searches.

 

You definitely want to upgrade the ECU situation. Too nice of a build to still be on the factory stuff. In terms of the sputtering issue that could be anything and if you have no way of logging it'll just be that harder to pinpoint and make corrections whether it's in the tune or you've got ignition, fuel issues etc. Interesting you Hobbs is activated at 7 as I always thought they were activated in the 4psi range unless you specified that psi range when you bought it.

I'm a 93 so the pcv routing is a little bit different but what I did was. From the ds of the intake where my pcv is located,...I'm running a one way check valve then into a water air oil separator before it goes back in the intake. Each valve cover has -10 bung's welded and then run lines to their own Stef breather catch can's. This was when I was running 18psi no issue but I run a lot less now but still kept the configuration the same.

 

Keep a close eye on that Opti spark as well, they're well known for having issues.
If you're standing strong with the LT1 platform, they make a kit that converts it to coil over plug that is miles better.

 

Torqhead is who makes the coil on plug setup. I bought one and it should get here tomorrow.

 

Racetronix only had 3 options, 7 was the lowest. 7 10 or 14 if i remember right.

 

Just to update the thread. Saw some smoke coming from pcv valve grommet. Pulled it out and it was nearly ripped in 2. Replaced it and this helped with a lot of the issues. Still wouldn't boost though, so i added more tension to the pulley. Boom, hitting 13 psi all day and and hauling. Still wants to stumble to accelerate after coming to a stop, but once the choppy rpm climb clears up, it's back to normal. For good measure, im going to install a mighty mouse catch and see if being able to run pcv improves the condition.

This car hauls *** now.